A slit lamp is generally understood to be an illumination apparatus that is used to view the front portion of the eye (lens and proximal vitreous body, and for inspection when fitting contact lenses). With the aid of the slit image, structures and layers in the eye can be better recognized during diagnostic and surgical procedures. Surgical slit lamps are used for the most part in combination with a surgical microscope in intraocular and especially in retinal surgery. By means of the rectangular illuminated field on the retina, membranes that have become diseased, which are very thin but nevertheless greatly reduce the patient's sight, can be detected early and successfully operated on.
Surgical slit lamps of this kind are on the market, for example, under the name “Leica Slit Illuminator,” and are described in Leica Selling Guide OPH 07/02, page 10.5.
The lamp housings of these surgical slit lamps are very bulky, however, because of the light source incorporated thereinto, which is usually a halogen lamp. In addition, such known surgical slit lamps contain not only the light source but also the imaging optics and the aperture that generates the slit. Efforts have been made to minimize the size of surgical lamps by at least replacing the halogen lamp with a fiber-optic light supply system (e.g. DE-C2-4227942).
The obligatory mounting location for surgical slit lamps is below the main objective of a surgical microscope. Bulky structures at this mounting location are undesirable, however, because they reduce the open working distance and are thus disadvantageous for the overall handling of the surgical microscope.